Dissolving microneedles for long-term storage and transdermal delivery of extracellular vesicles

Highly Active Frozen Nanovesicles Microneedles for Senile Wound Healing via Antibacteria, Immunotherapy, and Skin Regeneration

Senile wound healing risks a variety of health complications and makes both economic and psychological burdens on patients greatly. Poor activity of aged dermal fibroblasts (A-FBs) and local disordered immunoreaction in the deep dermis contribute to delayed wound healing. Therefore, the locally complex microenvironment in deep requires additional processing. Herein, a novel double-layer hyaluronic acid methacrylate (HAMA)/polyvinyl alcohol (PVA) microneedle patch (MNP) coated by young fibroblast-derived exosomes (Y-EXOs) (Y-EXOs@HAMA/PVA MNP) is presented for deep drug delivery, aged wound healing and immunoregulation. A spraying and freeze-drying method is applied for keeping the bioactivity of the nanovesicles. An ideal loading of Y-EXOs and enhanced strength for penetration have realized after circulation for times. The Y-EXOs@HAMA/PVA MNP shows an excellent influence on delayed wound healing of aged skin with active A-FBs, more deposition of collagen and less production of IL-17A compared with application of aged fibroblast-derived exosomes (A-EXOs). Moreover, the content microRNAs in Y-EXOs and A-EXOs are sequenced for further study. This study initiatively demonstrates that Y-EXOs have effective function on both anti-aging and anti-inflammation and Y-EXOs@HAMA/PVA MNP is expected as a novel strategy for deep drug delivery for promoting hard wound healing in aged skin in future clinical application.

Cyclosporin A-loaded dissolving microneedles for dermatitis therapy: Development, characterisation and efficacy in a delayed-type hypersensitivity in vivo model

Several drugs can be used for treating inflammatory skin pathologies like dermatitis and psoriasis. However, for the management of chronic and long-term cases, topical administration is preferred over oral delivery since it prevents certain issues due to systemic side effects from occurring. Cyclosporin A (CsA) has been used for this purpose; however, its high molecular weight (1202 Da) restricts the diffusion through the skin structure. Here, we developed a nano-in-micro device combining lipid vesicles (LVs) and dissolving microneedle array patches (DMAPs) for targeted skin delivery. CsA-LVs allowed the effective incorporation of CsA in the hydrophilic DMAP matrix despite the hydrophobicity of the drug. Polymeric matrix composed of poly (vinyl alcohol) (5% w/v), poly (vinyl pyrrolidine) (15% w/v) and CsA-LV dispersion (10% v/v) led to the formation of CsA-LVs@DMAPs with adequate mechanical properties to penetrate the stratum corneum barrier. The safety and biocompatibility were ensured in an in vitro viability test using HaCaT keratinocytes and L929 fibroblast cell lines. Ex vivo permeability studies in a Franz-diffusion cell setup showed effective drug retention in the skin structure. Finally, CsA-LVs@DMAPs were challenged in an in vivo murine model of delayed-type hypersensitivity to corroborate their potential to ameliorate skin inflammatory conditions. Different findings like photon emission reduction in bioluminescence study, normalisation of histological damage and decrease of inflammatory cytokines point out the effectivity of CsA-LVs@DMAPs to treat these conditions. Overall, our study demonstrates that CsA-LVs@DMAPs can downregulate the skin inflammatory environment which paves the way for their clinical translation and their use as an alternative to corticosteroid-based therapies.

Micro Trojan horses: Engineering extracellular vesicles crossing biological barriers for drug delivery

The biological barriers of the body, such as the blood-brain, placental, intestinal, skin, and air-blood, protect against invading viruses and bacteria while providing necessary physical support. However, these barriers also hinder the delivery of drugs to target tissues, reducing their therapeutic efficacy. Extracellular vesicles (EVs), nanostructures with a diameter ranging from 30 nm to 10 μm secreted by cells, offer a potential solution to this challenge. These natural vesicles can effectively pass through various biological barriers, facilitating intercellular communication. As a result, artificially engineered EVs that mimic or are superior to the natural ones have emerged as a promising drug delivery vehicle, capable of delivering drugs to almost any body part to treat various diseases. This review first provides an overview of the formation and cross-species uptake of natural EVs from different organisms, including animals, plants, and bacteria. Later, it explores the current clinical applications, perspectives, and challenges associated with using engineered EVs as a drug delivery platform. Finally, it aims to inspire further research to help bioengineered EVs effectively cross biological barriers to treat diseases.

MiR-141-3p-Functionalized Exosomes Loaded in Dissolvable Microneedle Arrays for Hypertrophic Scar Treatment

Hypertrophic scar (HS) is a common fibroproliferative disease caused by abnormal wound healing after deep skin injury. However, the existing approaches have unsatisfactory therapeutic effects, which promote the exploration of newer and more effective strategies. MiRNA-modified functional exosomes delivered by dissolvable microneedle arrays (DMNAs) are expected to provide new hope for HS treatment. In this study, a miRNA, miR-141-3p, which is downregulated in skin scar tissues and in hypertrophic scar fibroblasts (HSFs), is identified. MiR-141-3p mimics inhibit the proliferation, migration, and myofibroblast transdifferentiation of HSFs in vitro by targeting TGF-β2 to suppress the TGF-β2/Smad pathway. Subsequently, the engineered exosomes encapsulating miR-141-3p (miR-141-3pOE -Exos) are isolated from adipose-derived mesenchymal stem cells transfected with Lv-miR-141-3p. MiR-141-3pOE -Exos show the same inhibitive effects as miR-141-3p mimics on the pathological behaviors of HSFs in vitro. The DMNAs for sustained release of miR-141-3pOE -Exos are further fabricated in vivo. MiR-141OE -Exos@DMNAs effectively decrease the thickness of HS and improve fibroblast distribution and collagen fiber arrangement, and downregulate the expression of α-SMA, COL-1, FN, TGF-β2, and p-Smad2/3 in the HS tissue. Overall, a promising, effective, and convenient exosome@DMNA-based miRNA delivery strategy for HS treatment is provided.

Topical drug delivery strategies for enhancing drug effectiveness by skin barriers, drug delivery systems and individualized dosing

Topical drug delivery is widely used in various diseases because of the advantages of not passing through the gastrointestinal tract, avoiding gastrointestinal irritation and hepatic first-pass effect, and reaching the lesion directly to reduce unnecessary adverse reactions. The skin helps the organism to defend itself against a huge majority of external aggressions and is one of the most important lines of defense of the body. However, the skin's strong barrier ability is also a huge obstacle to the effectiveness of topical medications. Allowing the bioactive, composition in a drug to pass through the stratum corneum barrier as needed to reach the target site is the most essential need for the bioactive, composition to exert its therapeutic effect. The state of the skin barrier, the choice of delivery system for the bioactive, composition, and individualized disease detection and dosing planning influence the effectiveness of topical medications. Nowadays, enhancing transdermal absorption of topically applied drugs is the hottest research area. However, enhancing transdermal absorption of drugs is not the first choice to improve the effectiveness of all drugs. Excessive transdermal absorption enhances topical drug accumulation at non-target sites and the occurrence of adverse reactions. This paper introduces topical drug delivery strategies to improve drug effectiveness from three perspectives: skin barrier, drug delivery system and individualized drug delivery, describes the current status and shortcomings of topical drug research, and provides new directions and ideas for topical drug research.

Microneedle-Mediated Transdermal Delivery of Genetic Materials, Stem Cells, and Secretome: An Update and Progression

Medical practitioners commonly use oral and parenteral dosage forms to administer drugs to patients. However, these forms have certain drawbacks, particularly concerning patients' comfort and compliance. Transdermal drug delivery presents a promising solution to address these issues. Nevertheless, the stratum corneum, as the outermost skin layer, can impede drug permeation, especially for macromolecules, genetic materials, stem cells, and secretome. Microneedles, a dosage form for transdermal delivery, offer an alternative approach, particularly for biopharmaceutical products. In this review, the authors will examine the latest research on microneedle formulations designed to deliver genetic materials, stem cells, and their derivatives. Numerous studies have explored different types of microneedles and evaluated their ability to deliver these products using preclinical models. Some of these investigations have compared microneedles with conventional dosage forms, demonstrating their significant potential for advancing the development of biotherapeutics in the future.

Advances in the Applications of Extracellular Vesicle for the Treatment of Skin Photoaging: A Comprehensive Review

Skin photoaging is a complex biological process characterized by the accumulation of oxidative damage and structural changes in the skin, resulting from chronic exposure to ultraviolet (UV) radiation. Despite the growing demand for effective treatments, current therapeutic options for skin photoaging remain limited. However, emerging research has highlighted the potential of extracellular vesicles (EVs), including exosomes, micro-vesicles, apoptotic bodies and liposomes, as promising therapeutic agents in skin rejuvenation. EVs are involved in intercellular communication and can deliver bioactive molecules, including proteins, nucleic acids, and lipids, to recipient cells, thereby influencing various cellular processes. This comprehensive review aims to summarize the current research progress in the application of EVs for the treatment of skin photoaging, including their isolation and characterization methods, roles in skin homeostasis, therapeutic potential and clinical applications for skin photoaging. Additionally, challenges and future directions in EVs-based therapies for skin rejuvenation are discussed.

Prediction of drug permeation through microneedled skin by machine learning

Stratum corneum is the outermost layer of the skin preventing external substances from entering human body. Microneedles (MNs) are sharp protrusions of a few hundred microns in length, which can penetrate the stratum corneum to facilitate drug permeation through skin. To determine the amount of drug delivered through skin, in vitro drug permeation testing is commonly used, but the testing is costly and time-consuming. To address this issue, machine learning methods were employed to predict drug permeation through the skin, circumventing the need of conducting skin permeation experiments. By comparing the experimental data and simulated results, it was found extreme gradient boosting (XGBoost) was the best among the four simulation methods. It was also found that drug loading, permeation time, and MN surface area were critical parameters in the models. In conclusion, machine learning is useful to predict drug permeation profiles for MN-facilitated transdermal drug delivery.

Microneedle systems: cell, exosome, and nucleic acid based strategies

Cells, exosomes, and nucleic acids play crucial roles in biomedical engineering, holding substantial clinical potential. However, their utility is often hindered by various drawbacks, including cellular immunogenicity, and instability of exosomes and nucleic acids. In recent years, microneedle (MN) technology has revolutionized drug delivery by offering minimal invasiveness and remarkable versatility. MN has emerged as an ideal platform for the extraction, storage, and delivery of these biological components. This review presents a comprehensive overview of the historical progression and recent advances in the field of MN. Specifically, it highlights the current applications of cell-, exosome-, and nucleic acid-based MN systems, while presenting prevailing research challenges. Additionally, the review provides insights into the prospects of MN in this area, aiming to provide new ideas for researchers and facilitate the clinical translation of MN technology.

Engineering Extracellular Vesicles as Delivery Systems in Therapeutic Applications

Extracellular vesicles (EVs) are transport vesicles secreted by living cells and released into the extracellular environment. Recent studies have shown that EVs serve as "messengers" in intercellular and inter-organismal communication, in both normal and pathological processes. EVs, as natural nanocarriers, can deliver bioactivators in therapy with their endogenous transport properties. This review article describes the engineering EVs of sources, isolation method, cargo loading, boosting approach, and adjustable targeting of EVs. Furthermore, the review summarizes the recent progress made in EV-based delivery systems applications, including cancer, cardiovascular diseases, liver, kidney, nervous system diseases, and COVID-19 and emphasizes the obstacles and challenges of EV-based therapies and possible strategies.

Responsive Microneedles as a New Platform for Precision Immunotherapy

Microneedles are a well-known transdermal or transdermal drug delivery system. Different from intramuscular injection, intravenous injection, etc., the microneedle delivery system provides unique characteristics for immunotherapy administration. Microneedles can deliver immunotherapeutic agents to the epidermis and dermis, where immune cells are abundant, unlike conventional vaccine systems. Furthermore, microneedle devices can be designed to respond to certain endogenous or exogenous stimuli including pH, reactive oxygen species (ROS), enzyme, light, temperature, or mechanical force, thereby allowing controlled release of active compounds in the epidermis and dermis. In this way, multifunctional or stimuli-responsive microneedles for immunotherapy could enhance the efficacy of immune responses to prevent or mitigate disease progression and lessen systemic adverse effects on healthy tissues and organs. Since microneedles are a promising drug delivery system for accurate delivery and controlled drug release, this review focuses on the progress of using reactive microneedles for immunotherapy, especially for tumors. Limitations of current microneedle system are summarized, and the controllable administration and targeting of reactive microneedle systems are examined.

Flexible Monitoring, Diagnosis, and Therapy by Microneedles with Versatile Materials and Devices toward Multifunction Scope

Microneedles (MNs) have drawn rising attention owing to their merits of convenience, noninvasiveness, flexible applicability, painless microchannels with boosted metabolism, and precisely tailored multifunction control. MNs can be modified to serve as novel transdermal drug delivery, which conventionally confront with the penetration barrier caused by skin stratum corneum. The micrometer-sized needles create channels through stratum corneum, enabling efficient drug delivery to the dermis for gratifying efficacy. Then, incorporating photosensitizer or photothermal agents into MNs can conduct photodynamic or photothermal therapy, respectively. Besides, health monitoring and medical detection by MN sensors can extract information from skin interstitial fluid and other biochemical/electronic signals. Here, this review discloses a novel monitoring, diagnostic, and therapeutic pattern by MNs, with elaborate discussion about the classified formation of MNs together with various applications and inherent mechanism. Hereby, multifunction development and outlook from biomedical/nanotechnology/photoelectric/devices/informatics to multidisciplinary applications are provided. Programmable intelligent MNs enable logic encoding of diverse monitoring and treatment pathways to extract signals, optimize the therapy efficacy, real-time monitoring, remote control, and drug screening, and take instant treatment.

Construction of Graphene Quantum Dot-based Dissolving Microneedle Patches for the Treatment of Bacterial Keratitis

Bacterial keratitis (BK) is an ophthalmic infection caused by bacteria and poses a risk of blindness. Numerous drugs have been used to treat BK, the majority suffered from limited effect owing to their backward antimicrobial and delivery efficacy. Herein, we evaluated the antibacterial effect of a cationic carbon-based nanomaterial, i.e., imidazole-modified graphene quantum dots (IMZ-GQDs), which exhibits disinfection rates of >90% against three typical Gram-positive strains within 3 h owing to the loss of membrane integrity and decline in membrane potential. For ocular application, we further developed IMZ-GQDs-loaded dissolving microneedle patches (IMZ-GQDs MNs) via a typical two-step micromolding method. IMZ-GQDs MNs showed sufficient dissolution and penetration for intrastromal delivery in vitro and successfully overcome the rabbit corneal epithelial layer in vivo. The excellent biocompatibility of IMZ-GQDs MNs was demonstrated both in cell and animal models, and they exhibited low cytotoxicity, low invasiveness and low ocular irritation. The topical application of IMZ-GQDs MNs has the benefits of both high antibacterial activity and effective drug delivery, thereby leading to the resolution of Staphylococcus aureus-induced BK in rabbits in 7 days. Therefore, IMZ-GQDs MNs is a promising approach for BK treatment, which is safe and efficient.

Gallium-modified gelatin nanoparticles loaded with quercetin promote skin wound healing via the regulation of bacterial proliferation and macrophage polarization

Background: Wound healing is a complicated process involving multiple cell components and can help the re-establishment of the skin's barrier function. Previous studies have pointed out that bacterial infection and sustained inflammatory reactions are the main causes of the delay of wound closure and scar formation during wound healing. The effect of current approaches for scar-free wound repair still faces many challenges, and alternative therapeutic methods are urgently needed to be established. Methods: The basic characteristics of the new-designed nanoparticles were clarified through the characterization of the material. The biocompatibility of the nanoparticles, as well as its effect on fibroblast function, anti-bacterial capacity, inflammation suppressive role, and the underlying mechanism were further verified by a panel of biochemical assays in vitro. Ultimately, pre-clinical rat model was employed to testify its role in wound healing and scar formation in vivo. Results: Firstly, gallium-modified gelatin nanoparticles loaded with quercetin was successfully established, displaying good biocompatibility and facilitative effect on fibroblast function. In addition, the nanoparticles showed prominent anti-bacterial and inflammation-suppressive effects. What's more important, the nanoparticles could also induce the polarization of macrophages from M1 to M2 phenotype to exert its inflammatory inhibitory role through TGF-β/Smad signaling pathway. Ultimately, in vivo experiment showed that the nanoparticles could effectively promote wound repair and inhibit scar formation during the process of wound healing. Conclusion: Taken together, the new nanoparticles have good anti-bacterial and anti-scar formation effects and great potential in the field of skin wound repair, which provides a promising therapeutic strategy for wound treatment.

An overview of synthesis, characterization, applications and associated adverse effects of bioactive nanoparticles

A particle with a diameter ranging from 1 to 100 nm is considered a nanoparticle (NP). Owing to their small size and high surface area, NPs possess unique physical, chemical and biological properties as compared to their bulkier counterparts. This paper describes various physico-chemical as well as green methods that can be used to synthesize different types of NPs including carbon-based, ceramic, metal, semiconductor, polymeric and lipid-based NPs. These methods can be categorized into either top-down or bottom-up approaches. Electron microscopy, atomic force microscopy, dynamic light scattering, X-ray diffraction, zeta-potential instrument, liquid chromatography-mass spectrometry, fourier transform infrared spectroscopy and thermogravimetric analysis are the techniques discussed in the characterization of NPs. This review provides an insight into the extraordinary properties of NPs that have opened the doors for endless biomedical applications like drug delivery, photo-ablation therapy, biosensors, bio-imaging and hyperthermia. In addition, NPs are also involved in improving crop growth, making protective clothing, cosmetics and energy reserves. This review also specifies adverse health effects associated with NPs such as hepatotoxicity, genotoxicity, neurotoxicity, etc., and inhibitory effects on plant growth and aquatic life. Further, in-vitro toxicity assessment assays for cell proliferation, apoptosis, necrosis and oxidative stress, as well as in-vivo toxicity assessment like biodistribution, clearance, hematological, serological and histological studies, are discussed here. Lastly, the authors have mentioned various measures that can be adopted to minimize the toxicity associated with NPs such as green synthesis, use of stabilizers, gene gun, polymer shell, microneedle capsule, etc.